It is well-established to manufacture ophthalmic lenses, and in particular contact lenses such as soft contact lenses, in a fully automated manufacturing process. In such a process, the contact lenses are typically molded by polymerizing and/or crosslinking a starting material so as to form the contact lens. Depending on the starting material used, it may be required or desired to place the lens in one or more treatment liquids, such as an extraction liquids, rinsing liquids and/or coating liquids. To achieve this, the lenses may be placed into containers which may be transported through one or more liquid baths. The containers may comprise a tubular body having openings in the tubular body. The openings in the tubular body of the container ensures that liquid is contained in the inner space of the tubular body of the container so that the lens is immersed in liquid during its transport through the one or more baths and is in contact with the respective treatment liquid. One embodiment of such container comprises a diaphragm having flexible fins extending from the tubular body towards the central axis of the container. This diaphragm having the flexible fins ensures that the lens is retained in the respective container during the transport of the container through the baths and thus prevents the lens from getting lost in one of the baths which may otherwise occur due to liquid flow generated by the movement of the containers through the baths.
Once the treatment of the lenses is finished, the lenses must be removed from the treatment liquid and transported to subsequent processing stations, e.g. inspections station, packaging stations, etc. Removing the lens from the treatment liquid is typically performed with the aid of a gripper having an outer distal end face having openings therein allowing a lens to be sucked against the distal end face of the gripper with the aid of a vacuum applied through the interior space of the gripper. For that purpose, the gripper is introduced into the liquid to a position close to the lens to be grasped and then the vacuum is applied through the interior of the gripper and through the openings in the distal end face of the gripper resulting in the lens being sucked against the distal (typically convex) end face. The gripper together with the lens attached to the distal end face is then removed from the liquid and the lens is transported to a destination location where it is released from the distal end face with the aid of overpressure applied through the interior space and through the openings in the distal end face of the gripper.
While this way of grasping and removing a lens from a liquid is known as being reliable, there is still room for improvement. For example, the vacuum applied through the interior of the gripper which causes lens to be sucked against the distal end face of the gripper is maintained during removal and transport of the gripper with the lens adhered to the distal end face. This vacuum may cause the lens to at least partly dry out which may damage the lens or render the lens useless. And in some instances, it may cause the lens to strongly adhere to the distal end face so that it is not reliably released therefrom upon the application of overpressure through the interior space and through the openings in the distal end face of the gripper.
Accordingly, it is an object of the invention to provide a gripper for grasping an ophthalmic lens immersed in a liquid, in particular a contact lens such as a soft contact lens, which does not have the above-mentioned drawbacks of conventional grippers. The gripper should be capable of reliably grasping the ophthalmic lens, retaining it during removal of the gripper from the liquid and during transport of the gripper to the destination location where the lens is to be released from the gripper. In particular, the grasped lens is to be handled carefully during grasping and transport and drying-out of the lens should be prevented. In addition, the gripper should be capable of being used in mass production of ophthalmic lenses such as soft contact lenses. Preferably, the gripper should be capable of removing the lens from each type of container, but in particular from a container of the type comprising the tubular body and the fins extending from the tubular body towards the central axis of the tubular body.